Temperature Effect on Electrical Resistivity Measurement Using an Embedded Sensor to Estimate Concrete Water Content
, Elie Mahfoud 2,3, Géraldine Villain 1,*, Jean-Paul Balayssac 2, Sérgio Palma Lopes 1, Yannick Fargier 1 and Béatrice Yven 4Round 1
Reviewer 1 Report
DEar Autors.
The paper describes the effect of concrete temperature on the electrical resistivity measurements using multi-electrode embedded sensor. The authors carried out several experiments in different conditions of temperature, water saturation and electrode configurations (transmission and Wenner). The results of the study are interesting and the quality of the manuscript is satisfactory.
I have just some specific comments:
- Line 280: … Table 2 shows that the value of Ea increases and the value of A ...
It will be: ... Table 3 shows that the value of Ea increases and the value of A ...
- Line 288: … [20 – 45 °C] and [45 – 60 °C]. Table 3 illustrates the percentage change in …
It will be: … [20 – 45 °C] and [45 – 60 °C]. Table 4 illustrates the percentage change in …
- Line 295: … Table 3 shows that the percentage change in resistivity ranges from 1.3 …
It will be: … Table 4 shows that the percentage change in resistivity ranges from 1.3 …
it is observed that for both wanenr and transmission configurations at the temperature between 25 and 45 °C, the resistivity changes for a saturation of 53.3% is more than 33.8%. however, it is understood in the manuscript that as saturation is low, the resistivity changes are high. can you give an explanation?
the research has been focused on the study of the laboratory and I found it lacking a field scale application as it can have several applications in civil works. So I recommend adding the application to the field scale.
Author Response
Dear Madam, Dear Sir,
First, we would like to thank the editor and the reviewers for their evaluation of this work and for all their comments and remarks. We found very useful and interesting suggestions and we are pleased to provide the following answers (bold). Moreover, the sentences added to improve the paper thanks to reviewer remarks are let visible in correction mode in the manuscript (in italics herein). We hope they will suit you and are happy to answer you if you have any further question.
With our best regards,
Géraldine Villain for all authors
Response to reviewer#1’s comments:
“DEar Authors,
The paper describes the effect of concrete temperature on the electrical resistivity measurements using multi-electrode embedded sensor. The authors carried out several experiments in different conditions of temperature, water saturation and electrode configurations (transmission and Wenner). The results of the study are interesting and the quality of the manuscript is satisfactory.
I have just some specific comments:
- Line 280: … Table 2 shows that the value of Ea increases and the value of A ...
It will be: ... Table 3 shows that the value of Ea increases and the value of A ...
- Line 288: … [20 – 45 °C] and [45 – 60 °C]. Table 3 illustrates the percentage change in …
It will be: … [20 – 45 °C] and [45 – 60 °C]. Table 4 illustrates the percentage change in …
- Line 295: … Table 3 shows that the percentage change in resistivity ranges from 1.3 …
It will be: … Table 4 shows that the percentage change in resistivity ranges from 1.3 …. “
We thank you for your interest. All the Table numbers have been changed.
“it is observed that for both Wenner and transmission configurations at the temperature between 25 and 45 °C, the resistivity changes for a saturation of 53.3% is more than 33.8%. however, it is understood in the manuscript that as saturation is low, the resistivity changes are high. can you give an explanation?”
Our conclusion is general, considering the 16 mean changes. For Wenner configuration, between 20 and 45 °C, the resistivity changes for a saturation of 53.3% is less than 33.8% but, as you observed, the change is more for 53.3% than for 33.8 in Table 4. In Table 2, you can see all the mean resistivity values and all the standard deviations. In heterogeneous concrete (due to coarse aggregates or air bubbles) we are satisfied with error (CV=SD/Mean) equal or less 10% but it can increase for low degrees of saturation. At T=45°C and S=33.8%, rho=883+/-279 Ohm.m. This strong uncertainty, certainly due to heterogeneities, induces an error in evaluating the changes calculated in Table 4: it can range from 1.5 to 3.4 considering the extremal possible cases.
In order to nuance, we add the following sentence on line 306: “Note that the measurement dispersion increases with high resistivity values, at low saturation degrees of concrete due to the presence of heterogeneities (coarse aggregates and air bubbles). Thus, high uncertainty can have an influence on the percentage of change per degree such as the value at 45°C and S=33.8%.”
“the research has been focused on the study of the laboratory and I found it lacking a field scale application as it can have several applications in civil works. So I recommend adding the application to the field scale.”
In this paper, we wanted to focus on the combined effects of temperature T and degree of saturation S because we really needed analytical equations to better evaluate S in thick reinforced concrete structures. To do this, we first needed tests under controlled conditions (in the laboratory). Then real structures in the field subjected to different uncontrolled exposure conditions will be studied. It is a good suggestion that corresponds to our further studies but results are not available yet.
Reviewer 2 Report
This paper shows excellent results and conclusions about measuring the resistance in concrete with the water contents at different temperatures. However, there are some mistakes and unknown parts in this manuscript. Please check and improve as follows:
"Table 2" in line 273 and line 280 may be "Table 3".
Author employed Arrhenius law and obtained Arrhenius parameters. However, there is no discussion about the detail meanings of them. What is the advantage of calculating the parameters?
The resistivity may change in the different kind of concrete. Can you apply your results to the other kind of concrete?
Please consider my question.
Best regards.
Author Response
Dear Madam, Dear Sir,
First, we would like to thank the editor and the reviewers for their evaluation of this work and for all their comments and remarks. We found very useful and interesting suggestions and we are pleased to provide the following answers (bold). Moreover, the sentences added to improve the paper thanks to reviewer remarks are let visible in correction mode in the manuscript (in italics herein). We hope they will suit you and are happy to answer you if you have any further question.
With our best regards,
Géraldine Villain for all authors
Response to reviewer#2’s comments:
“This paper shows excellent results and conclusions about measuring the resistance in concrete with the water contents at different temperatures. However, there are some mistakes and unknown parts in this manuscript. Please check and improve as follows:
"Table 2" in line 273 and line 280 may be "Table 3". “
We thank you also cheerfully for your comments.
All the Table numbers have been corrected.
“Author employed Arrhenius law and obtained Arrhenius parameters. However, there is no discussion about the detail meanings of them. What is the advantage of calculating the parameters?”
The definition and meaning of Arrhenius parameters are given lines 150-157. The most interesting results for our study, found in literature refer to Arrhenius law [30,31,35,40] so it seemed the best way to compare our results to literature ones. Meanwhile, it could be useful in further studies to include chemical analysis to interpret the deep meaning of Ea but it was not the goal of this study.
“The resistivity may change in the different kind of concrete. Can you apply your results to the other kind of concrete?
Please consider my question.
Best regards.”
Yes, the evolutions of resistivity versus S or T depend on the concrete mix. The coefficients depend on the concrete but the essential information concerns the function shape obtained in this study. So, calibration is required for new materials but can be limited to a very few of adjustment points, which will save a lot of time while increasing the accuracy of the evaluation of S thanks to resistivity.
In order to improve the paper conclusion, we add the following sentence on line 325: “The main information obtained in this study concerns the function describing the evolution of resistivity versus saturation degree or temperature. The coefficients depend on the concrete mix. So, for new materials, we recommend a calibration that can be limited to a very few of adjustment points, which will save a lot of time while increasing the accuracy of the saturation degree evaluation thanks to resistivity at different temperatures.”
Reviewer 3 Report
1.The picture is not clear, which affects the readability of the article
2.There are only 3 temperature (20, 45 and 60 °C) experiments in this paper. What is the basis of selection? In addition, what is the rationality of just doing these three temperatures?
Author Response
Dear Madam, Dear Sir,
First, we would like to thank the editor and the reviewers for their evaluation of this work and for all their comments and remarks. We found very useful and interesting suggestions and we are pleased to provide the following answers (bold). Moreover, the sentences added to improve the paper thanks to reviewer remarks are let visible in correction mode in the manuscript (in italics herein). We hope they will suit you and are happy to answer you if you have any further question.
With our best regards,
Géraldine Villain for all authors
Response to reviewer#3’s comments:
“1.The picture is not clear, which affects the readability of the article
2.There are only 3 temperature (20, 45 and 60 °C) experiments in this paper. What is the basis of selection? In addition, what is the rationality of just doing these three temperatures? “
1- The resolution of the figures has been improved according to the reviewer recommendations. We hope that this will facilitate the reading.
2-Thank you for this good question. The objective of the whole study is the development of new embedded PCB resistivity sensors to evaluate the profiles of saturation degree. They are validated in liquids, small concrete specimens [26] and big and thick reinforced concrete structures. But good quality concrete is difficult to dry rapidly to obtain convenient profiles of saturation degree. So, the thick structures are died in an oven at T=45°C then at T=60°C to accelerated drying. Resistivity is affected by this temperature changes as underlined by literature [19-22] given in introduction but less results are available showing T effect at 4 different degrees of saturation S. So, to analyze carefully the results in the big slab, we previously needed the study combining T and S that is presented in the present paper.
Moreover, the T range [20-45°C] will be useful when the sensors will be embedded in real RC structures because these temperatures are often encountered outside. For this purpose, in further studies, we intend to extend the T range to lower T, T=10°C for instance.
